A valve device is mounted in a fuel tank of a vehicle. The valve device prevents fuel in the fuel tank from leaking out when the vehicle turns sharply or is inclined. In addition, the valve device prevents excessive feeding of fuel into the fuel tank such that the fuel level in the fuel tank does not exceed a predetermined full fuel level.
For example, Patent Literature 1 describes a fuel tank evaporative emission control system. The fuel tank evaporative emission control system has: a casing having an end plate having a first and second openings and in which a lower space and an upper space are defined via the end plate; a straight fuel vapor discharge pipe that is connected to an upper portion of the casing so as to communicate with the upper space; a first float valve that is disposed in the lower space so as to rise and fall and closes the first opening when a fuel level in a fuel tank nearly reaches a full fuel level; a second float valve that is disposed in the lower space so as to rise and fall and closes the second opening when the fuel level in the fuel tank rises abnormally; and a relief valve that is disposed to an upper portion of the second opening and closes normally the second opening, and opens the second opening when an internal pressure in the fuel tank becomes equal to or higher than a predetermined value.
When the fuel level nearly reaches the full fuel level as a result of feeding fuel into the fuel tank, the first float valve closes the first opening. Thus, further feeding of fuel is restricted. On the other hand, when fuel oscillates in the fuel tank, the first float valve and the second float valve rise to thereby respectively close the first opening and the second opening. Thus, fuel is prevented from flowing into the fuel vapor discharge pipe, and fuel is prevented from flowing out of the fuel tank.